1. Field of the Invention
The present invention provides a novel improved manufacturing process for producing shape memory alloy rings.
2. Brief Description of the Related Art
Shape memory alloys, such as Nitinol, having been disclosed in U.S. Pat. No. 6,321,656 to Johnson (Nitinol ring used in venting of rocket casing), U.S. Pat. No. 6,293,020 to Julien (cutting blanks from a Nitinol sheet) and U.S. Pat. No. 5,312,152 to Woebkenberg, Jr. et al. (process utilized to preset a shape in a shape memory alloy). However, none of these patents discloses an efficient and simple method of producing shape memory alloy rings as taught herein.
Current methods of forming the shape memory alloy rings include spot and butt welding techniques. The use of materials with weld points in critical applications, however, remains suspect for safety and performance reliability.
There is a need in the art to provide a method of producing shape memory alloy rings that is simple and efficient, while providing increased reliable safety and performance characteristics. The present invention addresses this and other needs.
The present invention includes a method for producing a non-welded shape memory alloy ring comprising the steps of forming a wire segment comprising a shape memory alloy to a given length proportional to a desired ring size, wherein the wire has a given cross-sectional dimension proportional for a desired thickness and width, annealing the cut wire, roll flattening the annealed cut wire to the desired thickness and width, slitting the length of the roll flattened wire along the centerline to form a precursor, opening the slit and annealing the opened slit on a mandrel to form a non-welded ring. The preferred shape memory alloy includes Nitinol.
The non-welded ring is particularly applicable for use in rocket motor venting ring systems and/or coupling devices, such as pipe fittings.